Several kinds of ladybugs roam the United States, and most of them will never attempt to set up lodgings in your home en mass. The variety known as the Asian lady beetle (Harmonia axyridis), however, is another story. Introduced from the 1960s to the 1990s by the US Department of Agriculture as a means of controlling crop pests, these Asian natives quickly took root.
Ladybugs are a diverse group of insects that share a few things in common, including a remarkable red or orange half-bubble-shaped shell and an insatiable urge to eat aphids. Since the 1990s, reports of ladybug infestations in homes have been reported to University Extensions across the country. Various methods have been developed for controlling ladybugs, though complete eradication is unlikely.
When the Asian lady beetle begins to sense winter approaching and temperatures drop in September, they begin to search for winter protection. They tend to be attracted to illuminated surfaces with afternoon sun. Often, the lady beetles huddle together in attics and walls or behind loose-fitting trim pieces. Generally, they are not harmful to humans, but a secretion they emit has been implicated in various nasal and allergy symptoms of people living in ladybug-infested homes.
Ladybugs prefer certain kinds of houses over others. Homes on the edge of forested areas or near large fields are often their targets. Ladybugs seem to prefer two-story homes that have a high level of contrast. A white farmhouse with black shutters and a dark-colored roof or a dark-colored house with light-colored gutters are highly attractive to ladybugs.
Ladybugs tend to congregate on illuminated surfaces. They prefer afternoon sun on the southwest side of buildings. If you notice ladybugs collecting on the side of your home and sunning themselves, consider adding a shade or planting shade trees along that side to deter them.
The best method of control is prevention. Once ladybugs decide your home is the warmest place in town, they will tend to return year after year. You can prevent infestation, however, by sealing cracks in trim, soffits and around pipes with caulk. Larger holes may require more intricate patching.
Once an infestation has set up, it may be difficult to evict your new tenants. Various methods have been examined, but the most effective by far is simply vacuuming the insects out of the walls. The insects will become irritated, however, and emit a foul-smelling yellowish liquid in to your vacuum. The University of Nebraska suggests inserting a knee-high nylon stocking into the hose wand to create a sort of ladybug net. When they spray their yellow fluid, it won't get passed the nylon. Make sure to dispose of the bugs outside of the home. A sealed home will be safe from re-infestation, so it is safe to release them alive.
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